Field
The present disclosure relates to an organic light-emitting display device.
Description of the Related Art
Organic light-emitting display devices can be fabricated to be relatively light and thin, since organic electroluminescent (EL) devices or organic light-emitting diodes (OLEDs) that can emit light themselves are used therein. In addition, organic light-emitting display devices are not only advantageous in terms of power consumption, because they are driven at low voltages, but also have desirable qualities such as the ability to implement a range of colors, rapid response rates, wide viewing angles, and high contrast ratios. Thus, organic light-emitting display devices for next-generation displays have been actively researched.
Light generated by an organic light-emitting layer of an organic light-emitting display device is emitted from the organic light-emitting display device through several components of the organic light-emitting display device. However, a portion of light generated by the organic light-emitting layer may fail to exit the organic light-emitting display device and be trapped therewithin, thereby causing a problem of low light extraction efficiency in the organic light-emitting display device.
Specifically, for an organic light-emitting display device having a bottom emission structure, about 50% of light generated by the organic light-emitting layer may be trapped within the organic light-emitting display device through total internal reflection or light absorption by an anode electrode while about 30% of light generated by the organic light-emitting layer may be trapped within the organic light-emitting display device through total internal reflection or light absorption by a substrate. That is, about 80% of light generated by the organic light-emitting layer may be trapped within the organic light-emitting display device, and only about 20% of light may be emitted outwardly, leading to poor light extraction efficiency.
To improve the light extraction efficiency of organic light-emitting display devices, a microlens array (MLA) has been attached to an overcoat layer of an organic light-emitting display device. However, even when an MLA is attached to the overcoat layer of the organic light-emitting display device, a large amount of light is trapped within the organic light-emitting display device, leading to a problem in which only a small amount of light is emitted outwardly.